Ship&#39;s propeller.



PATENTED MAR. '7, 1905 F. H. GRAWERT-ZELLIN.

I SHIPS PROPELLER.

APPLICATION FILED APR, 4, 190

MODEL.

gnuautoz Witnesses 63%;

lf STATES Patented March "2, 19055.

PATENT OFFICE.

SHllPS PHOPELLEFI.

SPECIFICATION forming part of Letters Patent No. 784,109, dated March 7, 1905.

Application file April 4, 1904. Serial No. 201,692. (Modeh) To all (Uh/07771 it petty concern:

Be it known that I, FRITZ H. GRAWERT- ZELLIN, a resident of the city of New York, State of New York, have invented certain new and useful Improvements in Ship-Propellers, of which the following is a full and complete specification.

The object of my invention is to provide a propeller of greater efficiency than has been hitherto attained for reciprocating engines and which is especially designed. for high angular velocity, as is the case with steam-turbines, for which my propeller is particularly adapted.

It is generally known that the elliciency of a screw-propeller does not exceed fifty per cent, the lateral displacement of a part of the water by the cenfrifugal force produced by the revolving screw resulting in a considerable loss. Therefore it has been the object of all constructors to reduce this lateral displacement by varying the form of the generatrix and the pitch. However, such modilications have not increased the elliciency of the screw to an appreciable extent.

After years of experiments I have succeed ed in designing a screw-propeller with forwardlyinclined concave helicoids merging to a point in the axis, with the result of gaining consid erably in speed over other propellers under like conditions, as has been proven by various tests.

In the drawings, Figure l is a plan View of the propeller. Figs. 2 and 3 are rear and front views, respectively, showing in dotted lines horizontal cross-sections through the right-hand blade, taken on lines A B and (l 1), respectively, seen from the right. Fig. l is a horizontal section on line E F of Fig. 2 looking from above.

1) represents the forwardly-inclined blades; (4 the hub, the latter merging with the former into a point (Z in the .axis of the propeller, as plainly shown in the drawings, thus constituting part of the helicoid. The plane, as shown in Fig. 2, also indicates the curve which generates said helieoid.

l-Iavim thus described my invention, what I claim as new, and desire to protect by Letters Patent, is

A screw-propeller having a plurality of forwardly-inclined concave blades, the working surfaces of which extend to and merge in a point in the axis of the propeller, substantially as described.

W itnesses:

Aneus'r ZINSSER, J12, Tn nononn HANSEN. 

